Flexible selection of a hybrid automatic repeat request (HARQ) process identifier from a HARQ process identifier pool

An apparatus for wireless communication at a user equipment (UE), comprising:

• one or more memories storing processor-readable code;
• and
• one or more processors coupled with the one or more memories, at least one processor of the one or more processors operable to cause the UE to:
• select, in association with a delay parameter for an uplink communication, a hybrid automatic repeat request (HARQ) process identifier from a plurality of HARQ process identifiers included in a HARQ process identifier pool, the HARQ process identifier being associated with the uplink communication;
• transmit an indication of the HARQ process identifier;
• and
• transmit the uplink communication;
• wherein all data packets in a transmission buffer of the UE are expired;
• and
• wherein at least one of the one or more processors is operable to cause the UE to:
• select, from the data packets in the transmission buffer, a subset of data packets for the uplink communication in association with at least one of:
• an expiration time associated with the subset of data packets,
• a selection order parameter, or
• a first-in-first-out (FIFO) parameter.